Types of Wedge Gate Valves

Rising stem wedge gate valve

The rising stem wedge gate valve is the valve in which the stem is fixed to the gate. Due to this design, the stem rises when the valve is opened. As such, this type of valve makes it easy for the valve operator to know when to open and close fluid flow. It also makes it easy to lubricate the valve stem once it rises above the valve bonnet. The stem is machined with screws, making it easy to rotate as it moves up or down. A packing component is placed between the stem and the bonnet to help prevent fluid leakage and the entrance of contaminants into the valve. The packing is usually replaced after some time as it wears out due to the stem up and downwards movement. This type of valve occupies a lot of space due to stem movement above the valve bonnet; thus, it is only installed where the area is not limited.

Figure: Rising stem wedge gate valve.

Non-rising stem wedge gate valve

The non-rising stem wedge gate valve employs a stem that, when the handwheel is rotated, the stem rotates but does not rise above like in a rising stem valve. As such, the stem turns as the wedge disc rises and lowers inside the valve. Wedge gate valve manufacturers recommend this valve for use where space is limited since they do not occupy much installation space like the rising stem type. These valves are manufactured with a visual pointer that helps the valve operator know when to close or open the valve.

Figure: Non-rising stem wedge gate valve.

Electrically actuated wedge gate valve

This type of wedge gate valve is operated using an electric actuator. Electric actuators are devices that create motion by using an electric motor. The motor works by converting electrical energy into mechanical energy. The mechanical energy is responsible for the force needed to run the wedge gate valve. Electric actuators are easier to integrate into the wedge gate valve than pneumatic or hydraulic actuators. These actuators are also programmed, making it easy to automate the valve, which is necessary for most industrial applications. These valves are also very safe and convenient as they are not susceptible to cause contamination or leakage that may happen in hydraulic actuated valves. As such, these valves are considered safer and cleaner, especially in pharmaceuticals and food industries where high levels of hygiene are demanded. They are also easy to operate, maintain, and install.

Figure: Electric actuated wedge gate valve.

Pneumatically actuated wedge gate valve

This valve is operated by converting compressed air into kinetic energy using a pneumatic actuator. The kinetic energy provides the force needed to turn the valve stem so that the valve disc can either open or close fluid flow. The actuator operates by compressing gas or air to levels past atmospheric pressure. Due to the compressed air, the actuator creates a controlled rotary motion which is then directed to the valve stem for valve operation. The air used in the actuator is filtered before being used to ensure it is free from contaminants and solids. These valves are very reliable and safe. They are thus suitable for use in applications that need high levels of hygiene, such as beverages and foods.

Figure: Pneumatic actuated wedge gate valve.